Further heavy fighting took place today in the Syrian capital, Damascus, and the northern city of Aleppo.
Activists said government forces had stormed Hajar al-Aswad, a southern suburb of Damascus, and that the situation for residents was desperate.
State media said troops had killed many of what they called “terrorists”.
Earlier, Amnesty International warned that indiscriminate air and artillery strikes were causing a dramatic rise in civilian casualties in Idlib and Hama.
The report said the plight of people in the two provinces had been under-reported because world attention had focused on Damascus and Aleppo.
Further heavy fighting took place today in Damascus and the northern city of Aleppo
Meanwhile, Iranian Foreign Minister Ali Akbar Salehi held talks with President Bashar al-Assad and other officials in Damascus.
Ali Akbar Salehi said a solution to the conflict, which the UN estimates has left at least 20,000 people dead, lay “only in Syria and within the Syrian family”.
Rebels have also taken full control of the Tal al-Abyad border crossing with Turkey after a lengthy battle with government forces overnight, according to Turkish officials and witnesses.
The crossing is further to the east than any of the others previously captured by rebels, and could make it easier for them to get fighters and ammunition in and out of Syria.
On Wednesday, opposition activists said the military was attacking the south-western Damascus suburbs of Muadhamiya, Jadidat Artouz and Kanakir, Qudsaya to the north-west, and the southern districts of Qaddam, Assali, Yalda and Hajar al-Aswad.
They posted videos online which they said showed helicopter gunships firing rockets on Hajar al-Aswad, as well as the bodies of some of the more than 20 people they said had been killed in the assault. The army was destroying and setting houses on fire, they added.
State media said troops had moved into Hajar al-Aswad and clashed with an “armed terrorist group” near a cemetery, eliminating “a number of its members”, and that others had been killed as streets were “cleansed”.
The Syrian Observatory for Human Rights, a UK-based activist group, later said rebel fighters had announced their withdrawal from Hajar al-Aswad, Qaddam and Assali after weeks of violent clashes.
Activists also reported that the bodies of at least 20 people executed by government forces had been found in the north-eastern district of Jobar.
In Aleppo, government forces had bombarded several central areas surrounding the Old City, including Bab al-Hadid and Bab al-Nasr, and also attacked the outlying districts of Hananu and al-Bab, they added.
The Local Co-ordination Committees, an activist network, said more than 62 people had so far been killed across the country on Wednesday, including 30 in Damascus. It put the death toll on Tuesday at 160.
The reports of violence came as Amnesty International said indiscriminate air attacks and artillery strikes by Syrian government forces are killing, maiming, and terrorizing civilians in the Idlib, Jabal al-Zawiya and north Hama regions.
Donatella Rovera, Amnesty’s senior crisis response adviser, who recently returned from northern Syria, said there was evidence that the army and air force were increasingly using battlefield weapons in residential areas where government troops had been forced out by opposition forces, with disastrous consequences for civilians.
“They are using in equal measure air-delivered, large, old, Soviet-era unguided bombs – free-fall bombs – the opposite of smart bombs,” she said.
“They are dropped over an area. There’s no way you can target them at a specific target or specific building.”
“They fall over people’s houses, over markets, in the street. Many of those who were killed and injured are children. Every day, in the field hospitals, on the ground, in the streets and in people’s homes I was seeing the disastrous consequences of these attacks on civilians.”
Amnesty’s report says the group carried out first-hand field investigations in the first half of September into attacks which killed 166 civilians, including 48 children and 20 women, in 26 towns and villages.
In a separate development, a Syrian general who defected to the opposition told the Times newspaper that the president had discussed using chemical weapons in the conflict, and even whether they should be transferred to the Lebanese Shia Islamist movement, Hezbollah.
“We discussed this as a last resort – such as if the regime lost control of an important area such as Aleppo,” General Adnan Sillu said.
Forty eight Iranian pilgrims have been kidnapped from a bus in the vicinity of a shrine near the Syrian capital Damascus, reports say.
Iranian diplomats blamed the abduction, from close to the Shia shrine of Sayyida Zainab, on “armed groups”.
Syrian state television later gave the same account of the incident.
Meanwhile, fresh fighting has been reported around Damascus, and in the northern city of Aleppo, where rebels are trying to secure their positions.
The Iranian consul in Damascus said the whereabouts of the abducted pilgrims was known.
Syrian state-run news agency Sana said the Iranians had been kidnapped by “armed terrorist groups” and that Syrian authorities were “working to handle the situation”.
Thousands of Iranians travel each year to Syria to visit the pilgrimage site in the mostly Shia district of Sayyida Zainab, which has seen heavy fighting in recent weeks.
There have been several other reports of groups of Iranian pilgrims being kidnapped in Syria in recent months, with most later being freed.
In May, 11 Lebanese Shia pilgrims were abducted in Syria while returning from Iran.
They were released after being held for three days, but the incident sparked violence across Lebanon, where the crisis in Syria has heightened sectarian tensions.
Forty eight Iranian pilgrims have been kidnapped from a bus in the vicinity of a shrine near the Syrian capital Damascus
Meanwhile, fresh fighting was reported in Syria’s two biggest cities on Saturday.
Most areas of Aleppo where rebels are entrenched have been bombarded by government forces and clashes have been reported in several districts.
Video footage posted by activists showed a military jet flying over what they said was the rebel-held quarter of Salah al-Din followed by a loud explosion.
Activists reported clashes in several areas too, including around the officers’ club and a political security headquarters.
Government forces seem to now be pushing harder in the crucial battle for Aleppo.
Syrian state television reported that troops had inflicted huge losses on what it called “terrorist mercenaries” in Salah al-Din and in other nearby areas too, our correspondent adds.
There have been skirmishes in which rebels have done rather well, he says, seizing three police stations and retaking a fourth on Friday, and rebels are “incrementally” increasing the size of the area they hold.
The rebels have “remarkable” defence capability in Salah al-Din where government tanks had been trying to enter, but as an area full of narrow twisting lanes, it is perfect for guerrilla warfare, he adds.
However, the full thrust of the armour and the artillery from the regime side has not been seen yet, he adds.
The focus of the fighting is also on the southern edge of Damascus where shelling and gunfire were reported from the Tadamon quarter, despite it having been earlier stormed by government forces.
Shooting and explosions were also being heard in some central parts of the capital, and activists reported clashes too on the western side of the city, in and around Dumar.
Earlier, Russia and China condemned a UN General Assembly resolution passed on Friday which criticized the Security Council for failing to halt the violence in Syria.
Moscow’s UN envoy, Vitaly Churkin, told reporters the resolution was one-sided and supported the armed opposition.
Western nations praised the resolution, which passed by 133 votes to 12 with 31 abstentions.
It criticizes both the UN’s own Security Council and the government of Syrian President Bashar al-Assad for its use of violence.
The assembly debated the resolution, which was proposed by Saudi Arabia, shortly after the resignation of UN-Arab League envoy Kofi Annan and the failure of his six-point peace plan.
Activists say more than 20,000 people – mostly civilians – have died in 17 months of unrest.
According to reports from activists and residents, the Syrian capital Damascus has seen some of the heaviest fighting of the conflict so far.
Mortar and small-arms fire was reported in several areas as government forces clashed with the Free Syrian Army.
The fighting came as UN and Arab League envoy Kofi Annan prepared to meet Russia’s foreign minister for talks on the Syrian crisis.
Russia has been backing Syrian President Bashar al-Assad’s regime.
Kofi Annan is expected to urge Foreign Minister Sergei Lavrov to put pressure on the Syrian authorities to begin a political transition..
The International Committee of the Red Cross (ICRC) has said the conflict in Syria is now in effect a civil war.
It means combatants across Syria are now subject to the Geneva Conventions and could be liable for war crimes prosecution in the future.
The ICRC had previously regarded only the areas around Idlib, Homs and Hama as warzones.
Syrian capital Damascus has seen some of the heaviest fighting of the conflict so far
Clashes between government forces and Free Syrian Army rebels seem to be creeping ever closer to the heart of Damascus and the centre of the regime’s power.
Mortars were reportedly used on the southern edge of the city, in areas like Tadhamon and Midan and around nearby Palestinian refugee camps.
Activists said clashes continued into the early hours of the morning.
A convoy of army reinforcements was reported to have been attacked by rebels in Kfar Sousa to the west, leading to further clashes there.
Residents were said to be fleeing some areas, while in other parts of the city protesters blocked motorways with burning tyres.
There has been frequent trouble in these areas – barely three miles (4-5 km) from the centre – for months.
But as with many of the suburbs ringing the city slightly further out, all the government’s repeated efforts to stifle defiance have failed.
The government has denied that it had used heavy weapons in its attack on the village of Tremseh on Thursday.
Activists initially described fighting in Tremseh, which is near the city of Hama, as a massacre of dozens of civilians, but later accounts suggested most of the dead were armed rebels.
UN observers at the scene have said Syrian forces used heavy artillery, tanks and helicopters, but Damascus denies those allegations and said just two civilians had been killed.
The accusations, if proved, would mean Damascus had broken an agreement it made with UN and Arab League envoy Kofi Annan.
Further pressure was put on the government of President Bashar al-Assad when the International Committee of the Red Cross, which oversees the Geneva Conventions, said fighting had now spread beyond the three hotspots of Idlib, Homs and Hama.
Spokesman Hicham Hassan said Syria was now regarded as a “non-international armed conflict”, which is the technical term for civil war.
“What matters is that international humanitarian law applies wherever hostilities between government forces and opposition groups are taking place across the country,” he said.
The statement is significant because it is the Red Cross’ job to monitor the conduct of the fighting, and to tell warring parties what their obligations are.
Under the Geneva Conventions, indiscriminate attacks on civilians, attacks on medical personnel or the destruction of basic services like water or electricity are forbidden and can be prosecuted as war crimes.
From now on, all those fighting in Syria are officially subject to the laws of war, and could end up at a war crimes tribunal if they disobey them.
The ICRC’s announcement echoes both the UN’s head of peacekeeping Herve Ladsous and President Assad, who has said the country is at war.
Some 16,000 people are thought to have been killed since the uprising against Bashar al-Assad’s regime began in March 2011.
UN diplomats are attempting to agree a way forward for the organization’s monitoring mission in the country.
The mission’s mandate runs out on Friday, and Western nations are trying to get Russia and China to agree to a strengthened resolution authorizing sanctions.
Kofi Annan’s six-point plan:
1. Syrian-led political process to address the aspirations and concerns of the Syrian people
2. End to violence by all sides; army troops to stop using heavy weapons and withdraw to barracks
3. Parties to allow humanitarian aid
4. Authorities to free political detainees
5. Authorities to ensure freedom of movement for journalists
Several civilians and police officers have been killed in two separate explosions in the Syrian capital Damascus, state TV announced.
A broadcast described the blasts as “terrorist” attacks. Preliminary reports suggested vehicles packed with explosives had been detonated, it said.
It said intelligence and police buildings were hit and the cause was not known.
Details of the reports cannot be independently verified as access to Syria for journalists is restricted.
Dozens of people have been killed in bomb attacks in Damascus and the second city Aleppo in recent months, which the government also blamed on terrorists.
The opposition has accused the authorities of staging some of those incidents.
The latest blasts came two days after the first anniversary of the uprising against President Bashar al-Assad, which UN estimates say has left more than 8,000 people dead.
State TV showed pictures of charred bodies, burned-out vehicles and bloodstains on the streets.
It described one body as being that of a terrorist.
It said buildings housing the criminal police and aviation intelligence had been targeted.
Opposition sources also said security buildings had been hit.
Fresh anti-government protests were held on Friday in cities across Syria.
And there was a return of violence to the Damascus suburbs – the first significant fighting there since government forces imposed military control some weeks ago.
Clashes between rebel fighters and the army were reported in several other parts of the country.
President Bashar al-Assad insists his troops are fighting “armed gangs” seeking to destabilize Syria.
On Friday, UN and Arab League special envoy Kofi Annan renewed calls for an end to fighting and for unimpeded humanitarian aid for Syria.
Speaking to UN Security Council members, Kofi Annan said he was sending a team to Damascus to discuss setting up a new international monitoring mission.
The international community remains divided on Syria, with Russia and China both blocking UN Security Council resolutions on Syria and aid groups from 27 countries urging them to condemn the government’s use of violence.
But the two permanent members have backed Kofi Annan’s peace mission.